1. Field of the Invention
This invention relates to a semiconductor device having a TAB (Tape Automated Bonding) tape, and more particularly to connection between electrode pads and leads.
2. Description of the Related Art
There is a TCP (Tape Carrier Package) developed in accordance with the development of semiconductor device packages each having many pins. A TAB tape to be used in the TCP consists of a polyimide film and leads formed on the polymide film. The leads are formed by etching a copper film adhered to the polyimide film by an adhesive. The leads are connected to pads formed on a semiconductor chip through bumps.
A pad pitch has recently been fine, and accordingly the cross section of a lead has been changed from a trapezoid to a triangle. This is because a fine pad pitch means a fine lead width and lead pitch. As a result, it is very difficult to etch the copper film, the leads are formed to have a wedge-shaped cross section.
When the lead is connected to the pad by a single point bonding method, the wedge-shaped lead will easily be slipped from a bump provided on the pad. This makes it difficult to reliably bond the lead to the pad, and also may cause shortcircuiting of the leads. If the lead is thinner to prevent it from having a wedge-shaped cross section, the bonding strength in the case of ILB (Inner Lead Bonding) or OLB (Outer Lead Bonding) is reduced. Therefore, it is not desirable to thin the thickness of lead. The same can be said of a gang bonding method.